JPH08167646A - Simox substrate, manufacture of simox substrate and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To realize an SIMOX substrate with a thick silicon single crystalline thin film having two or more kinds of film thicknesses. CONSTITUTION: The SIMOX substrate has a silicon single crystalline thin film 25 of two or more kinds of different film thicknesses (that is, there are two or more kinds of depths from a substrate surface to a buried oxide film 26). After a silicon oxide film mask 23 is partially arranged in a desired region on a silicon single crystalline substrate 21, oxygen ion is implanted and high temperature treatment is performed for it. A film thickness of the silicon oxide film mask 23 is selected not to completely check oxygen ion implantation but to allow oxygen ion concentration to peak at a desired depth in the silicon single crystalline substrate 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon substrate and a method for manufacturing the same, and more particularly to SIMOX (SEPARATION BY
IMPLANTED OXYGEN) substrate and its manufacturing method.

[0002]

2. Description of the Related Art In recent years, semiconductor LSIs have undergone various modifications due to demands for higher integration, higher speed, lower power consumption, etc. In order to achieve further higher speed and lower power consumption, parasitic capacitance must be used. It is necessary to significantly reduce As one of the most promising methods to significantly reduce the parasitic capacitance, SOI (SILICO
N ON INSULATOR) structure is considered.

In an SOI substrate, a silicon single crystal thin film is formed on an insulating film, and a transistor is formed on the silicon single crystal thin film. As an example, when a MOS transistor is formed on an SOI substrate in which the silicon single crystal thin film on the insulating film is extremely thin, the bottoms of the source electrode and the drain electrode are in direct contact with the insulating film, so that the parasitic capacitance can be significantly reduced. In the 0.5 μm rule MOS process that is becoming mainstream at the mass production level, the depth of the source electrode and the drain electrode is about 200 nm, so a MOS transistor that makes full use of the low parasitic capacitance that is a characteristic of the SOI structure is used. In order to form it, it is necessary to use an SOI substrate in which the thickness of the silicon single crystal thin film on the insulating film is 200 nm or less.

SIMOX (SEPARATION BY IMPLANTED
The OXGEN) substrate is a kind of SOI substrate, and the extremely thin silicon single crystal thin film as described above can be easily formed on the buried silicon oxide film. Figure 5 shows the conventional SI
The structure of a MOX board | substrate is shown. The method of manufacturing the SIMOX substrate is as follows. First, oxygen ions are applied to the silicon single crystal substrate 51, for example, with an energy of 180 KeV and a dose of 7
e17 / cm2 injection. After that, high-temperature heat treatment is performed at, for example, 1320 ° C. for 6 hours to form a uniform buried silicon oxide film 52, and crystal defects are removed by ion implantation, and a high quality silicon single crystal thin film is formed on the buried silicon oxide film 52. 53 is formed.

[0005]

However, in the conventional SIMOX substrate formed by the above method, the thickness of the silicon single crystal thin film on the buried silicon oxide film is constant over the entire surface (the depth of the buried silicon oxide film is small). For example, in the case of BiCMOS process in which MOS transistor and Bipolar transistor are mixedly mounted on the same substrate, the optimal silicon single crystal thin film thickness is different between MOS transistor and Bipolar transistor. It had a problem that it had to be sacrificed. For example, as shown in FIG. 6, when the vertical high-speed bipolar transistor 614 is formed on the SIMOX substrate, the film thickness of the silicon single crystal thin film needs to be 0.4 μm or more. In that case, the MOS transistor 613 formed on the same substrate should Since the bottoms of the source electrode 606 and the drain electrode 605 are not in contact with the buried oxide film, the performance of the MOS transistor is equivalent to that formed on the silicon bulk substrate, and the merit of using the SOI substrate cannot be obtained at all. Also, if a silicon single crystal thin film with a thickness of about 0.2 μm, which is suitable for MOS transistors, is used, vertical Bipolar transistors cannot be formed, and horizontal Bipolar
You can't get it without using a transistor.

In view of the above problems, the present invention is capable of forming two or more different types of devices on a silicon single crystal thin film having a film thickness optimal for each device, and a method of manufacturing the same. The purpose is to provide.

[0007]

In order to solve the above problems, a SIMOX substrate and a method for manufacturing a SIMOX substrate according to the present invention have two or more kinds of silicon single crystal thin films having different thicknesses in the same substrate plane. (There are two or more depths from the substrate surface to the buried oxide film within the same substrate surface) S
An IMOX substrate is provided.

In order to realize this structure, a mask material is partially arranged in a desired region on a silicon single crystal substrate, oxygen ions are implanted, and high temperature heat treatment is performed. At this time, the film thickness of the mask material is selected so that the implantation of oxygen ions is not completely blocked but the concentration peak of the implanted oxygen ions comes to a desired depth in the silicon single crystal substrate. .

[0009]

According to the present invention, by providing the SIMOX substrate having the silicon single crystal thin film having two or more kinds of film thicknesses according to the above-mentioned constitutions, two or more kinds of transistors are optimal for each transistor on the same SIMOX substrate. It is possible to form a thin silicon single crystal thin film.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a sectional structure of a SIMOX substrate according to a first embodiment of the present invention. A buried silicon oxide film 12 is formed in a silicon single crystal substrate 11, and a silicon single crystal thin film 13 for device formation is present on the buried silicon oxide film 12, which is similar to the conventional SIMOX substrate. However, the film thickness of the silicon single crystal thin film 13 has a distribution in the surface of the silicon single crystal substrate, and the film thickness is, for example, 400 nm in the region 15 where the bipolar transistor is formed. 14, the film thickness is 200 n, for example.
The difference is that it is m. In addition, the SIMO of the present invention
As a characteristic of the X substrate, the surface of the silicon single crystal substrate 11 is flat, and the film thickness of the silicon single crystal thin film 13 is changed by changing the depth from the surface of the silicon single crystal substrate to the embedded silicon oxide film. I am letting you.

FIG. 2 shows the SIMOX of this embodiment shown in FIG.
It is sectional drawing which shows the manufacturing process which forms a board | substrate.

First, as shown in FIG. 2A, a silicon oxide film 22 is deposited on a silicon single crystal substrate 21, and a silicon oxide film mask 23 is formed on an arbitrary portion by a usual photolithography process and etching process. Form (Fig. 2
(B)). Here, the silicon oxide film mask 23 is formed to play a role of controlling the depth in the silicon single crystal substrate of the oxygen ions implanted in the next oxygen ion implantation step, but the ion implantation is performed. In order to set the oxygen ion depth to a desired depth, it is necessary to appropriately select the film thickness of the silicon oxide film mask 23. In this embodiment, the silicon oxide film 23 has a thickness of 250 nm, for example.
To form.

Next, as shown in FIG. 2 (c), oxygen ions, for example, have an energy of 180 keV and a dose of 7e17 /
Inject under the condition of cm ² . Then, in the region on the silicon single crystal substrate where the silicon oxide film mask 23 does not exist, the peak of the concentration of oxygen ions is about 400 from the surface.
On the other hand, in the region where the silicon oxide film mask 23 is present, the peak concentration of oxygen ions is present at about 150 nm from the surface of the silicon single crystal substrate.

Finally, as shown in FIG. 2 (d), after removing the silicon oxide film mask 23, for example, at 1320 degrees, 6
A high temperature heat treatment is performed for a time to form a uniform buried silicon oxide layer 26, and a crystal defect is removed by ion implantation to form a high quality silicon single crystal thin film 25 on the silicon oxide film 26. Under the conditions of this embodiment, the thickness of the buried oxide film 26 is about 80 nm. Further, the film thickness of the silicon single crystal thin film 25 in the region where the silicon oxide film mask does not exist is about 350 nm and the film thickness is 250 n.
The film thickness of the silicon single crystal thin film 25 in the region where the m silicon oxide film mask 23 exists is about 100 nm.

By the method of manufacturing a SIMOX substrate shown in FIG. 2 as described above, it is possible to form a SIMOX substrate in which the position where the embedded silicon oxide film is formed is different in the depth direction of the substrate, and two or more different types of film thickness are different. A SIMOX substrate having a silicon single crystal thin film can be formed.

The SIMOX substrate formed in this embodiment is made into Bi
When applied to a CMOS device, it is desirable that the silicon single crystal film thickness of the Bipolar transistor portion is 400 nm or more, but it is not very realistic in the current technology to implant oxygen ions with high dose and high energy of 180 keV or more. Therefore, for example, when a film thickness of 450 nm is required for a Bipolar transistor, Does implantation with high energy is not performed, and Does implantation is performed with low energy. At that time, the position where the embedded silicon oxide film is formed is the above-mentioned. After being formed shallower than in the embodiment, silicon may be epitaxially grown to a thickness of 100 nm from the state of FIG. In this case, the silicon single crystal thin film 2 in the region where the silicon oxide film mask 23 did not exist
The thickness of 5 becomes 450 nm, and the silicon oxide mask 2
The film thickness in the region where 3 was present is 200 nm.

FIG. 3 is a sectional view of a BiCMOS device formed on the SIMOX substrate described above. Vertical Bipol
n + buried layer 308 of the ar transistor 314, and
The bottom portions of the source electrode 306 and the drain electrode 305 of the MOS transistor 313 are both embedded silicon oxide film 30.
Since it is in direct contact with 2, Bi with a very small parasitic capacitance
It is possible to form a high-performance BiCMOS device having both polar transistors and MOS transistors.

In this embodiment, the SIMOX substrate having the silicon single crystal thin film having two kinds of film thickness and the manufacturing method thereof are shown. However, the film thickness of the silicon oxide film mask is changed in two or more steps, and S having a silicon single crystal thin film having three or more kinds of film thicknesses by changing the implantation conditions of S
It is also possible to form an IMOX substrate.

(Embodiment 2) FIG. 4 shows a sectional structure of a SIMOX substrate according to a second embodiment of the present invention. In FIG. 4, a buried silicon oxide film 42 is formed in a silicon single crystal substrate 41.
A silicon single crystal thin film 43 for forming an element is present thereabove. Here, the feature of this embodiment is that the film thickness of the silicon single crystal thin film is 0 at a predetermined portion 44 in the surface of the silicon single crystal substrate. That is, the islands of the silicon single crystal thin film 43 are completely isolated on the embedded silicon oxide film 42.

When the SIMOX substrate in which the islands of the silicon single crystal thin film 43 are completely isolated as described above is used, it is not necessary to form an element isolation such as a trench isolation which is originally formed in the subsequent steps, The process can be shortened.

The structure of this embodiment is SIMO of the first embodiment.
It can be formed by exactly the same method as the manufacturing method of the X substrate. However, it is necessary to change the film thickness of the silicon oxide film mask and the implantation conditions of oxygen ions so that the embedded silicon oxide film is formed on the surface of the silicon single crystal substrate. Specifically, for example, under the oxygen ion implantation conditions shown in FIG. 2 in the first embodiment, if the thickness of the silicon oxide film mask is set to about 350 nm, the region where the silicon oxide film mask exists will be Since the silicon single crystal thin film does not exist on the surface, the embedded silicon oxide film can be exposed on the substrate surface.

It is needless to say that the MOS transistor formation region, the Bipolar transistor formation region, and the element isolation region can be simultaneously formed on the same SIMOX substrate by combining this embodiment and the first embodiment. Yes.

[0024]

As described above, according to the present invention, a SIMOX substrate having two or more kinds of silicon single crystal thin films having different film thicknesses can be formed. Therefore, two or more kinds of devices can be formed on the same SIMOX substrate. Is formed on a silicon single crystal thin film most suitable for each device, so that an extremely high-performance integrated circuit with small parasitic capacitance can be formed. Further, according to the present invention, the element isolation region can be formed at the same time when the SIMOX substrate is formed, and the element isolation process can be simplified.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view of a SIMOX substrate according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the manufacturing process of the SIMOX substrate according to the first embodiment of the present invention.

FIG. 3 is a structural cross-sectional view of a device formed on a SIMOX substrate according to the first embodiment of the present invention.

FIG. 4 is a structural sectional view of a SIMOX substrate according to a second embodiment of the present invention.

FIG. 5 is a structural sectional view of a conventional SIMOX substrate.

FIG. 6 is a BiCMO formed on a conventional SIMOX substrate.
Structural cross section of S device

[Explanation of symbols]

11, 21, 301, 41, 51, 601 Silicon single crystal substrate 12, 26, 302, 42, 52, 602 Embedded silicon oxide film 13, 25, 303, 43, 53, 603 Silicon single crystal thin film 23 Silicon oxide film mask 314, 614 Vertical Bipolar transistor 313, 613 MOS transistor 305, 605 Source electrode 306, 606 Drain electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H01L 27/08 331 E 27/12 E 29/786 9056-4M H01L 29/78 613 Z 9056-4M 621 (72) Inventor Doichi Matsumoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A SIMOX substrate having a silicon single crystal substrate, a buried silicon oxide film layer formed on the silicon single crystal substrate, and a silicon single crystal thin film layer formed on the silicon oxide film layer. And the SIMOX
The buried silicon oxide layer in a predetermined region of the substrate,
A SIMOX substrate, which is present in the other region above the buried silicon oxide film layer. 2. A SIMOX substrate having a silicon single crystal substrate, a buried silicon oxide film layer formed on the silicon single crystal substrate, and a silicon single crystal thin film layer formed on the silicon oxide film layer. And the SIMOX
The buried silicon oxide layer in a predetermined region of the substrate,
The SIM which is present above the buried silicon oxide film layer in the other region, and the surface of the buried silicon oxide film in the predetermined region is exposed.
OX substrate. 3. A step of partially disposing a mask material in a desired region on the surface of the silicon single crystal substrate, and implanting oxygen ions into the surface of the silicon single crystal substrate using the mask material as a mask to form a buried oxide film layer. A method of manufacturing a SIMOX substrate, which includes a step of forming, a step of removing the mask material, and a step of performing heat treatment after the oxygen ion implantation. 4. A step of partially disposing a mask material in a desired region on the surface of the silicon single crystal substrate, and implanting oxygen ions into the surface of the silicon single crystal substrate using the mask material as a mask to form a buried oxide film layer. A method of manufacturing a SIMOX substrate comprising: a step of forming, a step of removing the mask material, and a step of performing heat treatment after the oxygen ion implantation, wherein a lower part of the mask material when the mask material is removed. A method of manufacturing a SIMOX substrate, wherein the surface of the buried oxide film layer is exposed. 5. The method of manufacturing a SIMOX substrate according to claim 3, wherein the mask material is permeable to the implanted oxygen ions. 6. A step of partially disposing a mask material in a desired region of the surface of the silicon single crystal substrate, and implanting oxygen ions into the surface of the silicon single crystal substrate using the mask material as a mask to form a buried oxide film layer. A step of forming, a step of removing the mask material, a step of performing a heat treatment after the oxygen ion implantation, and a step of forming a MOS transistor in a region of the silicon single crystal substrate surface where the mask is arranged, And a step of forming a bipolar transistor on a region of the surface of the silicon single crystal substrate where the mask is not arranged.